Effective Approaches for Estimating the Functionalization Pattern of Carboxymethyl Starch of Different Origin

Three types of differently prepared carboxymethyl starches were analyzed by HPLC and ¹H-NMR spectroscopy after chain degradation. In derivatives obtained in the conventional manner with values of the degree of substitution (DS) up to 0.85; glucose, mono- and di-O-carboxymethyl glucose were detected as building units. Comparison with statistic calculations revealed an even distribution of functional groups along the chain. ¹H-NMR studies confirmed a preferred substitution at the 2 position of the repeating unit. Comparable results were obtained for the carboxymethyl ether of amylose, amylopectin and β-cyclodextrin. The analysis of carboxymethylated starch samples prepared using a new synthesis concept via a reactive microstructure revealed a high DS achieved in a one-step synthesis as well as a non-statistic distribution of carboxymethyl groups along the chain. A significant amount of 2,3,4,6-tetra-O-functionalization, caused by the branched structure of starch, was found. Moreover, carboxymethylation of 6-O-triphenylmethyl starch and subsequent detritylation yields a regioselectively functionalized polymer consisting not only of the expected mono- and di-O-carboxymethylated repeating units but also containing a significant amount of 2,3,4-tri-O-functionalized anhydro-glucose units.     

Starch Derivatives of High Degree of Functionalization. 7. Preparation of Cationic 2‐Hydroxypropyltrimethylammonium Chloride Starches

Water‐soluble starch derivatives containing quarternary ammonium groups of high degree of substitution are prepared by reacting starch with 2,3‐epoxypropyltrimethylammonium chloride in different reaction media. The reaction was carried out in aqueous sodium hydroxide under dissolution of the product, in dimethyl sulfoxide homogeneously, and completely heterogeneously in ethanol/water. The DS values of up to 1.1 in an one‐step synthesis of the samples can be controlled by adjusting the molar ratio of cationization agent to anhydroglucose unit and are only slightly dependent on the amylose content of the starting starch material. A two‐step reaction yields products of a DS of up to 1.5. The structure of the cationic starch derivatives was confirmed by means of elemental analysis, FTIR‐ and NMR spectroscopy as well as GC‐MS.     

A comparative study on the transport of L(-)malic acid and other short-chain carboxylic acids in the yeast Candida utilis: Evidence for a general organic acid permease

Cells of the yeast Candida utilis grown in medium with short-chain mono-, di- or tricarboxylic acids transported L(-)malic acid by two transport systems at pH 3·0. Results indicate that probably a proton symport for the ionized form of the acid and a facilitated diffusion for the undissociated form were present. Dicarboxylic acids such as succinic, fumaric, oxaloacetic and α-ketoglutaric acids were competitive inhibitors of the malic acid for the high-affinity system, suggesting that these acids used the same transport system. In turn, competitive inhibition uptake studies of labelled carboxylic acid in the low-affinity range indicated that this system was non-specific and able to accept not only carboxylic (mono-, di- or tri-) acids but also some amino acids. Additionally, under the same growth conditions, C. utilis produced two mediated transport systems for lactic acid: a proton symport for the anionic form which appeared to be a common monocarboxylate carrier and a facilitated diffusion system for the undissociated acid displaying a substrate specificity similar to that observed for the low-affinity dicarboxylic acid transport. The mediated carboxylic acid transport systems were inducible and subjected to repression by glucose. In glucose-grown cells the undissociated dicarboxylic acids entered the cells slowly by simple diffusion. Repressed glucose-grown cells were only able to produce both transport systems if an inducer, at low concentration (0·5%, w/v), was present during starvation in buffer. This process was inhibited by the presence of cycloheximide indicating that induction requires de novo protein synthesis. If a higher acid concentration was used, only the low-affinity transport system was detectable, showing that the high-affinity system was also repressed by high concentrations of the inducer.     

In vitro production of specific polysaccharides: isolation and structure of an antitumor active β-glucan from Phytophthora parasitica

Polysaccharides are known to be an important group of biological polymers which are of great interest for industrial use. Besides their physical properties, their chemical structures can be the base for specific applications in medicine. Various polysaccharides are known to exhibit an antitumor activity, which is thought to be host mediated by a stimulation of the host's immune system. A β-1.3/1.6-glucan P isolated from the cell walls of Phytophthora parasitica Dastur (Mating type A1, 1828) exhibited strong antitumor activity against Sarcoma-180 in mice. Growth of the fungus was markedly stimulated by β-sitosterol and calcium ions. The fungus was shown to be thiamine heterotroph. At optimal growth conditions up to 30 g (dry weight) of fungal mycelium could be harvested within 5 days in 81 of culture medium, which represented ~6 g of cell wall material. A specific water-soluble cell wall glucan P was isolated by extraction with hot water and purification by ion-exchange and Con A chromatography. By methylation analysis it was shown that the β-glucan consisted of 1.3-, 1.3.6- and terminal-glucose residues in a molar ratio of 5:1:1. Sequential Smith degradations combined with methylation analyses showed the presence of mono- as well as di- and trisaccharides as side chain constituents in a ratio of 9:2:3. A structure of the antitumor active β-1.3/1.6-glucan P is proposed.     

The lipids of the alga Spirulina

The blue-green alga, Spirulina maxima, examined in the form of a spray-dried powder, contains 11% of lipid, which has been analysed in detail with a view to establishing both the classes of lipid present and their fatty acid profiles. The dominant lipids are mono-, di- and probably higher galactosyldiglycerides and phosphatidyl glycerol. Unlike other algae, Spirulina synthesises cis-6-cis-9-cis-12 octadecatrienoic acid in contrast to its 9–12–15 isomer.     

Exposure to phthalic acid,phthalate diesters and phthalate monoesters from foodstuffs: UK total diet study results

Phthalates are ubiquitous in the environment and thus exposure to these compounds can occur in various forms. Foods are one source of such exposure. There are only a limited number of studies that describe the levels of phthalates (diesters, monoesters and phthalic acid) in foods and assess the exposure from this source. In this study the levels of selected phthalate diesters, phthalate monoesters and phthalic acid in total diet study (TDS) samples are determined and the resulting exposure estimated. The methodology for the determination of phthalic acid and nine phthalate monoesters (mono-isopropyl phthalate, mono-n-butyl phthalate, mono-isobutyl phthalate, mono-benzyl phthalate, mono-cyclohexyl phthalate, mono-n-pentyl phthalate, mono-(2-ethylhexyl) phthalate, mono-n-octyl phthalate and mono-isononyl phthalate) in foods is described. In this method phthalate monoesters and phthalic acid are extracted from the foodstuffs with a mixture of acidified acetonitrile and dichloromethane. The method uses isotope-labelled phthalic acid and phthalate monoester internal standards and is appropriate for quantitative determination in the concentration range of 5–100 µg kg^–1. The method was validated in-house and its broad applicability demonstrated by the analysis of high-fat, high-carbohydrate and high-protein foodstuffs as well as combinations of all three major food constituents. The methodology used for 15 major phthalate diesters has been reported elsewhere. Phthalic acid was the most prevalent phthalate, being detected in 17 food groups. The highest concentration measured was di-(2-ethylhexyl) phthalate in fish (789 µg kg^–1). Low levels of mono-n-butyl phthalate and mono-(2-ethylhexyl) phthalate were detected in several of the TDS animal-based food groups and the highest concentrations measured corresponded with the most abundant diesters (di-n-butyl phthalate and di-(2-ethylhexyl) phthalate). The UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) considered the levels found and concluded that they did not indicate a risk to human health from dietary exposure alone.     

Preparation and Calcium Complexation of Oxidized Polysaccharides. Part I: Oxidation of Maltodextrins and Starch with Alkaline Sodium Hypochlorite

The oxidation of maltodextrins and starch with aqueous alkaline sodium hypochloride has been studied. At an oxidant level of 3 moles hypochlorite per anhydroglucose unit at pH 8–9, a C2, C3-glycol-cleaved dicarboxy polysaccharide was obtained containing up to 45% ring-opened glucose units. Hydrolysis of the oxidation products yielded (apart from glucose) erythronic and glyoxylic acids, but no glucuronic acid evidencing the absence of C6-oxidation. The average degree of polymerization of the products ranged from 14 to 87 and indicated severe chain degradation during the oxidation. The products were shown to be effective calcium complexing agents and behaved as regular polyelectrolytes with identical complexing sites.     

Spezifische Bestimmung von Mono-, Di- und Triglyceriden in Modellmischungen und in Soja?l

Zusammenfassung Es wird eine Methode zur spezifischen Bestimmung von Mono-, Di- und Triglyceriden beschrieben. Dazu werden nach dünnschichtchromatographischer Trennung des Glycerid-Gemisches die Mono-, Di- und Triglyceride nach der Verseifung enzymatisch bestimmt. Die Genauigkeit der Methode wurde an Gemischen aus Glycerin-mono-, -di- und -tristearat sowie Glycerin-monostearat, Glycerin-distearat und Glycerin-trioleat überprüft. Der Mono- und DiglyceridGehalt einiger Sojabohnen-Öle wurde bestimmt.Diese Methode eignet sich sowohl für die Ermittlung größerer Mono- und Diglycerid-Gehalte als auch zur Analyse von Spuren von Mono- und Diglyceriden neben Triglyceriden. Ohne eine spezielle Anreicherung können im Öl noch 6g (5 · 10^–3%) Mono- und 10g (1 · 10^–2 %) Diglycerid analysiert werden.

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Specific determination of mono-, di- and triglycerides in model mixtures and in soyabean-oil

Summary A method for the specific determination of mono-, di- and triglycerides is described. After the thin-layer chromatographic separation of the glyceride mixture, the mono-, di- and triglycerides are determined enzymatically after saponification. The accuracy of the method was tested with mixtures of glycerol-mono-, -di- and -tristearate. The content of mono- and diglycerides of some soyabean oil samples was determined.The method proved suitable for the detection of larger contents of mono- and diglycerides as well as for the analysis of trace amounts of mono- and diglycerides besides triglycerides. Without a special enrichment process it is possible to analyse as low amounts as 6 g (5 · 10^–3%) mono-and 10g (1 · 10^–2%) diglycerides in the oil.

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Für die sorgfältige und gewissenhafte Ausführung der Analyse danke ich Fräulein R.Kröger und Fräulein M.Kröpelm.     

Starch Derivatives of High Degree of Functionalization. 4. Homogeneous Tritylation of Starch and Subsequent Carboxymethylation

The synthesis of monomethoxytriphenylmethyl (MMtrityl) starch and the subsequent carboxymethylation of the 6‐O‐functionalized products were investigated. The trityIation both in N,N‐dimethylacetamide (DMA)/LiCl and in dimethyl sulfoxide (DMSO) occurred homogeneously. The highest degree of substitution of trityl groups (DS_TrityI) obtained after a single conversion step was 0.77 in both solvents. A complete functionalization of primary OH‐groups was achieved only with unsubstituted triphenylmethyl chloride in these reaction media. In case of monomethoxytriphenylmethyl chloride (MMTMC) as reagent an additional conversion step is necessary to synthesize products with a DS_TrityI = 1. The structure of the products was analyzed by FTIR‐ and ¹³C‐NMR spectroscopy. Subsequent carboxymethylation of the MMtrityl starch samples leads to products with a preferred functionalization of the unprotected secondary OH‐groups. After removal of the trityl moieties, the DS_CM and the distribution of carboxymethyl groups within the anhydroglucose unit was investigated by means of HPLC and ¹H‐NMR spectroscopy. The carboxymethylation was more effective at O‐2 than at O‐3. In case of ether products with DS_Trityl < 1 a partial substitution of the primary OH group took place as well.     

Heterogeneity of caprine kappa-casein macropeptide

The heterogeneity of caprine caseinmacropeptide (CMP) was determined by means of treatments with neuraminidase and acid phosphatase and analyses by anion exchange FPLC and reversed-phase (RP)-HPLC, with on-line and off-line electrospray ionization mass spectrometry. The main CMP components were two non-glycosylated and di-phosphorylated forms, as well as two other mono-phosphorylated species, each corresponding to a genetic variant of caprine kappa-casein due to the silent substitution Ile/Val at position 119. Asialo-aglyco mono- and di-phosphorylated forms were found in the ratios 8-14% and 86-92%, respectively. Approximately 36% of caprine CMP was glycosylated. Based on the obtained molecular masses, the occurrence of tri-, di- and monosaccharide-containing di-phosphorylated CMP are reported, assuming that N-acetylgalactosamine, galactose, N-acetyl and N-glycolylneuraminic acids would constitute the main monosaccharides of caprine CMP. CMP microheterogeneity due to the genetic polymorphism was also observed in the glycosylated forms.     

In-vitro and in-vivo studies on digestion of dietary fibre components in a broiler chicken diet based on rye

In an in-vitro system, endogenous enzymes, as well as an added enzyme preparation, degraded both soluble and insoluble dietary fibre components in a diet based on rye endosperm, insoluble arabinose and xylose residues were not as efficiently degraded in vitro by the endogenous enzymes as the insoluble glucose residues. Broiler chickens were fed on the diet with or without the supplementary enzyme. Enzyme supplementation generally improved the apparent ileal digestibility of the insoluble dietary fibre components while soluble dietary fibres, especially arabinoxylans, were enriched in the ileal digesta leading to negative digestibility values. ¹H-NMR spectra of arabinoxylans in digesta from chickens in combination with sugar analyses corroborated the results from the in-vitro study which indicated that the enzyme preparation preferentially degraded the soluble mono-substituted xylose residues while un- and disubstituted xylose residues were enriched.     

Predictors of polychlorinated biphenyl concentrations in adipose tissue in a general Danish population

Polychlorinated biphenyls (PCBs) are ubiquitously present in the environment and suspected of carcinogenic, neurological, and immunological effects. Our purpose was to identify predictors of adipose tissue levels of mono-, di-, and tri-ortho-substituted PCBs experienced by a general population and to establish whether predictors vary according to substitution group. In this study of 245 randomly selected persons from a prospective Danish cohort of 57,053 persons, we examined geographical area, age, lactation, BMI, and intake of eight major dietary groups as potential determinants of adipose concentrations of mono-, di-, and tri-ortho-substituted PCBs by linear regression analyses. Lactation, BMI, and intake of fruit, vegetables, and dairy products showed negative associations with PCB concentrations in adipose tissue in all models, and living in Copenhagen city, age, and consumption of fish (particularly fatty fish) were positively associated. The associations between several of the predictors and mono-ortho-substituted PCBs tended to differ from the associations found for di- and tri-ortho-substituted PCBs. In conclusion, geography, age, lactation, BMI, and consumption of fatty fish consistently predicted the concentration of PCBs in adipose tissue. Our results indicate that predictors of PCBs varied according to substitution group, suggesting that ortho-substituted groups should be analyzed separately.     

Homogeneous Synthesis and Characteri-zation of Quaternized Cellulose Derivatives in NaOH-urea Aqueous Solutions

Quaternized cellulose( QC) derivatives were synthesized by reacting cellulose with 3-chloro-2-hydroxypropyl trimethyl ammonium chloride( CHPTAC) in an aqueous solution of Na OH-urea. The chemical structures and physical properties of the obtained QC derivatives were characterized using nitrogen content analysis,Fourier transform infrared spectroscopy( FT-IR),~1H-nuclear magnetic resonance(1H-NMR),X-ray diffraction( XRD),and thermal gravity analysis( TGA). The FT-IR and ~1H-NMR results confirmed the successful introduction of cationic quaternary ammonium groups into the main chain of cellulose. A series of QC derivatives with the degree of substitution( DS) values ranging from 0. 33 to 0. 80 were derived by adjusting the molar ratio of CHPTAC to anhydroglucose unit( AGU) of cellulose,concentration of cellulose in the Na OH-urea solution,as well as reaction temperature and time. According to the DS values of the QC derivatives,the optimized synthetic conditions were as follows: 25℃ reaction temperature,3% cellulose in Na OH-urea solution,the molar ratio of etherification agent to glycosidic cellulose of 15∶ 1,and 12 h reaction time. The TGA and XRD results revealed that the crystalline structure was destroyed during etherification,and the thermal stability of the QC derivatives was lower than that of cellulose.     

Changes in the lipid and fatty acid composition during maturation of seeds of white mustard (Sinapis alba)

The oil content of the seeds of white mustard (Sinapis alba) was determined 3 weeks after flowering and at weekly intervals until seeds were matured. Examination of the lipid classes by quantitative t.l.c. showed that triglycerides were the major components at all stages and were accompanied by sterol esters, diglycerides and polar lipids; monoglycerides were only detected in the first 2 samples. The fatty acid composition of the total oil and the mono-, di- and triglycerides and sterol esters was determined by g.l.c. The 7 major fatty acids, namely palmitic, stearic, oleic, linoleic, linolenic, eicosenoic and erucic acids were present at all stages of maturity. The fatty acid composition of the triglyceride fraction was similar to that of the total oil whereas the mono- and diglycerides and sterol esters contained a relatively higher proportion of saturated fatty acids. Erucic acid, the major acid of the oil from mature seeds did not become the major acid until 35 days after flowering. The results are discussed in relation to pathways of lipid synthesis in higher plants.     

DEGRADATION OF GUAR GUM BY ENZYMES PRODUCED BY A BACTERIUM FROM THE HUMAN COLON

A strain of Bacteroides ovatus from the human colon was grown on guar gum, a highly-branched galactomannan which is widely used as a food additive. Growth on guar gum induced production o f extracellular enzymes which partially degraded and/or deaggregated guar gum. The enzymes rapidly reduced the viscosity of guar gum solutions, while breaking only a limited number of glycosidic bonds. The molecular weight (versus dextran standards) of the guar gum decreased sharply as the viscosity decreased. No mono-, di- or trisaccharides were produced during enzyme action, although small quantities of higher oligomers were present after longer (5–8 h) incubations. The enzyme had a sharp temperature optimum at 37°C for an incubation time of 60 min, but was stable for only a few hours at this temperature. These results demonstrate how enzymes produced and elaborated by human colon bacteria can markedly alter the physical properties of a dietary component which reaches the colon. Further studies of both substrate and enzymes will be required to establish the mechanism of this alteration and to establish how B. ovatus is able to utilize guar gum for growth.     

Quantenchemische MNDO-, AM1-, und PM3-Untersuchungen von α-D-Glucose-acetaten, -benzoaten und -(trichlor)acetaten als Modelle für die entsprechenden Amyloseverbindungen

Quantum Chemical MNDO-, AM1-, and PM3-Studies of α-D -Glucose Acetates, -Benzoates and -(Trichloro)Acetates as Models for the Respective Amylose Compounds. Heats of formation have been calculated for α-D-Glucose and also for its mono-, di- and trisubstituted derivatives (acetates, benzoates and (thrichloro)acetates in the positions 2, 3 and 6), applying the semiempirical quantum chemical methods MNDO, AM1 and PM3. When only one hydroxyl is substituted, the thermodynamic probability of generation decreases as 6>3>2 (acetates), 2>6>3 (benzoates) and 6>2>3 ((thrichloro)acetates). Generation of glucose monoacetate increases the reactivity of acetylation for both of the other OH groups. That was not established for benzoates and (trichloro)acetates. For comparison, the heats of formation have been calculated for all unbranched dodecanols and also for their acetates, benzoates and (trichlor)acetates. Enthalpies of reaction were estimated for all considered compounds taking into account the corresponding acid chlorides, one molecule of pyridine and the generation of pyridinium hydrochloride. It was shown that, generally, the reactivity of the dodecanols is higher than that of unsubstituted and substituted glucose. The results are discussed with regard to preparative application.     

Substituent Distribution in Hydroxyethyl Starch

The substituent distribution of hydroxyethyl starch has been determined at various degrees of substitution (MS = 0.03–1.9) by capillary gas chromatography of the silylated hydrolysate. In the monosubstituted derivatives 70–80% of the hydroxyethyl groups is attached to the C2 atom. The ratio of C3 to C6 monohydroxyethylated products changes from 2 to 0.2 when increasing the MS from 0.03 to 1.9. At high MS (around 2) the disubstituted products consist for about 50% of 2-hydroxyethoxyethyl derivative, which indicates a strong preference for the consecutive reaction of the newly formed hydroxyl group of 2 hydroxyethyl-anhydroglucose. The distribution of mono- and polysubstituted products is in agreement with a model of consecutive reactions with average relative rate constants for mono-, di- and higher substitution of 1.30, 1.05 and 0.85 respectively.     

Analytische Untersuchungen von phosphatvernetzten Stärken

Analytical Investigations on Phosphate Cross-Linked Starches. The phosphorylation is a method commonly employed for cross-linking starches intended for the food industry and other uses. The analytical methods by which phosphoric ester groups in the starch are detected, namely X-ray, fluorescence photometry, colorimetry as well as potentiometry, in the past were limited to relatively high degrees of substitution (D.S.). The technologically desired effects however, are often achieved with much lower degrees of substitution. By our improvement of the method described by Mitchell these very low D.S. levels can now be dertermined. The influence of the type of reagent, the reaction conditions on the ratio of mono- to diester as well as their effect on viscosity and relaxation time as technologically important properties are discussed.     

甘油酯的分析方法

分别采用薄层色谱(TLC)、正相HPLC对中性脂质进行分离.并分别采用密度扫描仪、蒸发光散射检测器、折光检测器对分离的样品进行了定性、定量分析.结果表明,3种方法都可实现甘油三酯(TG)、甘油二酯(DG)、甘油一酯(MG)、游离脂肪酸(FFA)的分离,而且1,3、1,2-DG位置异构体拆分明显.通过上述方法可以完成中间产物的监测及终产品的分析.